In a multi-layer interior permanent magnet synchronous motor, the d- and q-axis parameters vary nonlinearly according to different load conditions, consequently changing the level of saturation. The flux-linkage of d- and q-axis conveys ripple characteristics resulting from mechanical structure and degree of magnetic saturation. If the calculated flux-linkage is correct, the torque using the Maxwell stress tensor method is the same torque calculated by the flux-linkage. However, discrepancy between results exists. In this paper, the d- and q-axis flux-linkage, in consideration of the ripple characteristic, is calculated. Simulation results are then compared with experimental results.